Poll: Energy and Entropy.

[FalloutJack]

So, on this fine April 1st, I bring you...SCIENCE!

Just a little discussion thingy: I was reading an Isaac Asimov story - The Last Question - in regards to the question of entropy and the heat-death of the universe, or the running down of all things, or the intergalacic thinning to the point of non-existence.

There is a problem.

Now, we don't KNOW if the universe is a true infinity or not, because we just can't see that far, but... Given that the universe may be infinite, which is it that is true: That energy can be neither created nor destroyed, or that entropy will bring the total end of all that exists? The thought occurred to me that - all things being equal - one of these should be untrue. I don't know if all things ARE equal, but since the universe seems to tend to itself nicely, we can give it he benefit of the doubt for the purposes of discussion.

So, as stated, energy is here and always here, only changed in shape or form, never removed. It can be drawn out, but it exists in all things, for all materials in existence have a charge which allows them TO exist. On the other hand, all things which run on energy in some way or another will eventually expire. Plants and animals, people and particles, planets and suns - All of it will break down.

But if energy just moves around, never disappearing, is there entropy? Or are we just wrong about energy? What do you guys think?

 

[Queen Michael]

I might be wrong here, but isn't entropy about how order turns into chaos? As in, a pyramid won't get built by random forces of nature, but it'll break down if you leave it alone? And like how a cup of coffee will go cold automatically unless an outside force heats it?

That doesn't mean that things will stop existing. It just means that they won't be neat and ordered for long.

 

[Thaluikhain]

But if energy just moves around, never disappearing, is there entropy? Or are we just wrong about energy? What do you guys think?

Er, you are wrong about entropy there. Energy can't be created or destroyed, only changed into other forms, yes, but entropy is about having less usable energy. For example, our sun will eventually go out, it will still exist, but it won't be doing anything we'd consider important like providing light and heat to our solar system.

Things won't end as such, but we'd end up with a universe with no resources left to do anything, and it'd be more or less the same temperature all over.

 

[Neurotic Void Melody]

The energy would still exist, it would just stop being transformed and rest into a really spread out "heat" where energy would no longer be performing any work so to speak. The relaxed state of thermodynamic equilibrium; maximum entropy...2nd law of thermodynamics, which i shall cunningly steal and copy-paste from wiki, as the wording will always be better than mine;

The second law of thermodynamics states that the total entropy of an isolated system can only increase over time. It can remain constant in ideal cases where the system is in a steady state (equilibrium) or undergoing a reversible process. The increase in entropy accounts for the irreversibility of natural processes, and the asymmetry between future and past.

But really, there is so much to learn of the universe's complexities that it is impossible to state with certainty that it would function as a closed system. Then there is gravitational energy to account for. Quite a few unknowns, to say the least.
But the important take-away is you can still legitimately (and gleefully) depress everyone around you by bringing up the heat death of the universe without being contradictory, generally, for now.

 

[Glongpre]

Is there a way for energy to form into new suns? If there is all this energy spread out, could there not be some kind of mechanism which would bring a bunch together? I've always thought that maybe black holes do that. They suck up a bunch of stuff, make it really dense, and this becomes a new core for a star.

I think the universe is infinite, and for that to be true, there needs to be some mechanisms to keep a cycle going, or else we would have already hit entropy because the universe has already been existing for a long ass time before we evolved.

 

[Thaluikhain]

Is there a way for energy to form into new suns? If there is all this energy spread out, could there not be some kind of mechanism which would bring a bunch together? I've always thought that maybe black holes do that. They suck up a bunch of stuff, make it really dense, and this becomes a new core for a star.

Oh sure, bits of old stars can form new ones, but there's a limit to how far that works. Eventually you end up with lots of useless fuel in places fusion won't happen. Or you just fuse all the hydrogen, but the former will be more of an issue.

Black holes don't work like that, they are existing stars that've collapsed in on themselves, they don't uncollapse.

I think the universe is infinite, and for that to be true, there needs to be some mechanisms to keep a cycle going, or else we would have already hit entropy because the universe has already been existing for a long ass time before we evolved.

The universe is estimated to be around 14 billion years old, life some 2 billion years (IIRC).

Having said that, we don't know if the constants are constant. If not, heat death might not be the end, though I'd expect if the constants are changing, it'd be at a rate so slow it'd not make a difference until many times the time from now till heat death after then. Which would make the universe potentially infinite.

 

[FalloutJack]

Snip

You see? I'm already loving this. I may not have a full or proper understanding. On the otther hand, Queen Michael may be right. Let's engage.

Usable energy is something largely defined in terms of what a theoretical future human or otherwise being may be able to use, but then if the energy is not being destroyed, it's still there. The universe is full of energy, even in the blackness of space, between planets and stars.

Suppose there's no outside, that - upon creation - the universe filled all space which it could (because we really don't know otherwise at this point). If, at Event One, this was true, then it wouldn't be able to 'go' anywhere. Granted, black holes, and they play a part in one of my more interesting creation theories, but suppose nothing's leaving and just bouncing around in some form or another. Stars have been born under observation too, right?

How do we know that Elton John didn't get it all in one go with The Circle of Life, that it doesn't just all reform again continuously?

 

[Thaluikhain]

Usable energy is something largely defined in terms of what a theoretical future human or otherwise being may be able to use, but then if the energy is not being destroyed, it's still there. The universe is full of energy, even in the blackness of space, between planets and stars.

Well, when I meant usable, I didn't mean just by humans or aliens. For example, the sun works by fusing hydrogen into helium in its core. When the hydrogen in its core is sued up, it stops working (as the sun we know today). Hydrogen not at its core doesn't fuse, it's wasted from that point of view. It'll just sit there indefinitely as the sun cools down.

Also, that heat and light the sun is sending out, only a small fraction reaches our planets, much goes into space. After a certain distance you'd not be able to see it with a telescope. So, that energy has gone off and been wasted. It still exists, but not in a useful form.

Suppose there's no outside, that - upon creation - the universe filled all space which it could (because we really don't know otherwise at this point). If, at Event One, this was true, then it wouldn't be able to 'go' anywhere. Granted, black holes, and they play a part in one of my more interesting creation theories, but suppose nothing's leaving and just bouncing around in some form or another. Stars have been born under observation too, right?

Well, not quite, in that it takes longer than we've had decent astronomy to watch that sort of thing, but yeah, stars would be forming right now somewhere if we can see them. But you need to get lots of hydrogen in the same place. There's a limited amount of hydrogen around, once it's fused into helium you aren't getting it back. We'll run out eventually. Well, technically you can make helium into hydrogen, but any method of doing that will use more energy than you'd be able to get back by fusing it again. A lot of the energy goes into making the universe a tad warmer than absolute zero. Heat doesn't turn back into matter by itself.

How do we know that Elton John didn't get it all in one go with The Circle of Life, that it doesn't just all reform again continuously?

Well, everything we know about science says otherwise. For example, much of the materials in your computer were made from a dying star. They are going to sit on the Earth and not go and form new stars.

 

[Loop Stricken]

an Isaac Asimov story - The Last Question

Good little story that, one of my favourites.

Bacon.

 

[skywolfblue]

Usable energy is something largely defined in terms of what a theoretical future human or otherwise being may be able to use, but then if the energy is not being destroyed, it's still there. The universe is full of energy, even in the blackness of space, between planets and stars.

A boulder on top of a hill is easy to make energy out of, just push it slightly and it rolls down the slope.
To roll the boulder back up the hill though, takes energy, a lot of it.

The amount of energy is the same, but the FORM that energy takes is important.
Matter -> Energy is relatively straightforward. If an advanced civilization discovers an easy way to create antimatter, they could live long into the cold dark after all the stars burn out and all the usable hydrogen has been fused. However, once all the matter runs out...
Energy -> Matter is not quite so easy.

The energy is still "there" even in the Heat Death of the universe. It's just that empty space is warmed up by only a degree or two above absolute zero. Let's say that in the far future have a magic machine that can suck that thermal energy out of a large area of space and concentrate it. It'd take a volume of space bigger then a planet just to operate a flashlight. Let's assume that this magic machine sucks in thermal energy from the surrounding area at the speed of light, it wouldn't be able to suck in heat fast enough to meet the current daily US power usage. Space is too spread out.

 

[Satinavian]

Usable energy is something largely defined in terms of what a theoretical future human or otherwise being may be able to use, but then if the energy is not being destroyed, it's still there. The universe is full of energy, even in the blackness of space, between planets and stars.

If you take hot water and cold water and let it mix, you get warm water. That basically happens by itself. But you will never witness how warm water divides spontanous into hot and cold water. One direction is easy, the other direction is hard.

That is basically what entropy is about. There is one direction in which change can happen and one direction where it can't happen
Every process ever follows the same direction in the whole universe. Including all processes that are somehow part of life. You can never reverse it and even stopping it means freezing things in time as nothing ever is allowed to happen.


But this can't go on forever. The entropy that can exist is limited. And when the maximum is reached, no process creating entropy is possible anymore. Processes destroying entropy were never possible at all, so nothing can happen anymore and passage of time stops.

 

[Souplex]

You misunderstand. Entropy won't "destroy" everything, it will merely render it into a uniform state of minimal potential energy.
A ball at the top of a slope has high potential energy. A slight nudge and suddenly it's rolling.
A ball at the bottom of a slope has low potential energy. It's not going anywhere without an outside force exerting energy.
Basically a frozen lifeless wasteland.

 

[Bad Jim]

Entropy is irreversible because the laws of the universe are reversible.

That may sound strange but it is true. By 'reversible' I mean that you cannot transform a large number of states into a small number of states, because such a change loses information about how to reverse it. A consequence of this is that since there are so many more ways for a smoke-filled room to exist than a room with clear air and some combustible material, you cannot un-burn the smoke, except at the cost of increasing entropy elsewhere.

However, this is more an engineering principle than something nature must follow at all times. We cannot force entropy to decrease, but it is possible for entropy to naturally decrease as well as increase. The universe is statistically almost guaranteed to progress towards maximum entropy, but it is not strictly forced to.

In fact, if the universe has a finite number of potential states, we are guaranteed to get back to the Big Bang eventually. A loop of events which excluded the Big Bang but could nonetheless be reached from the Big Bang would require the universe to follow irreversible laws.

 

[Zen Bard]

Oh curse you Jack for making me crack open my Thermodynamics text book for the first time in 30 years!

Actually, this is a cool topic (so no curses were actually filed).

Couple of things;

Thing 1) Yes, the First Law of Thermodynamics states that "energy in a closed system can neither be created or destroyed". However, this doesn't mean there's a blob of energy just hanging out being all energized. It's in a constant transformative process, being given off as light, dissipated as heat or converting that heat into mechanical work. This is where Entropy comes in.

Thing 2) In the thermodynamic sense, Entropy does NOT equate to Chaos. If I recall, that bastard Rudolf Clausius (and anyone who's had to suffer through thermo knows exactly why I'm calling him a bastard) defined Entropy as "the loss of heat that can be converted into usable work."

Let's say you start a small fire and contain it in a tightly sealed jar (not vacuum sealed since oxygen is still required to feed the fire). Eventually, the fire will burn out because it will have consumed all the oxygen, wood, paper and whatever else you were burning. However ,the energy of that system has been transformed into (and now resides in) the ash, soot and other residue that are byproducts of that reaction. But none of that energy can be used to produce mechanical work.

That's entropy.

This what the "Heat Death" refers to. The energy in the universe is simply no longer usable.

Disclaimer: It's been a couple of decades since I've been in the Heat Transfer game. So if any of you bright young engineering students out there want to set me straight, by all means...feel free.

 

[FalloutJack]

Okay, because alot of people are talking specifically to me, I'm gonna make posts that I feel address what's being said to me and you guys just quote-respond to get my attention. Easier that way.

SO!

Hearing alot in this about the types of energy and that there appears to be only one direction and not looping back. Two things bother me. Everything you guys are saying makes enough sense to bode with what we have been able to know or reasonably theorize about space so far, but there's a couple of things I need to throw down, just in case, and some of you are gonna hurt me for doing that, because the complexity of the universe makes all our heads hurt. The two things are...

{1} The interaction of gravitational forces, dark matter, and dark energy. The universe is in a constant spin cycle. Everything is spinning around everything else because of its material weight, plus the interaction of other things. The universe isn't empty. The blackness of space has varying levels of denser materials and the unusual energies which interact with them, dark matter and dark energy. It seems as though, looking into it, that these two seem tto be responsible for the motive and at least some of the gravitational forces in the universe. (To wit, there is dark matter halo'd around our solar system, and it's presence appears to keep Pluto from flying off into some other galaxy.) Because there are alot of unknowns surrounding this, it may be possible that the birth of stars was aided by their presence. From that, I could possibly think that once things get small enough, they are easier to push around on the atomic/sub-atomic/even-smaller range towards unknown reactions that may force things back into the spotlight. Because the energy exists in some form and is never gone, the thinness of it may be easier to coerce by the natural characteristics of a universe we still do not fully understand.

{2} Quantum-level events. As you know, there is a point where things go so low that our ability to observe and separate them from other things becomes nigh-impossible. What is it, only CERN that can, or can Berkley and other places? I dunno. It's unreachable by any normal lab. The point is that there's a level of existance we are as blind to as the parts of the universe out of our total sight range. Presumably, everything interacts with quantum foam, but we don't know the fullness of it. Now, there was the point that the problem revolves around the remaking of materials that are expended during their interactions on the atomic/molecular level. If I were to bet on any place where - once things were down-and-out enough - you could get back your hydrogen and so on, it'd be in a quantum clusterflux. I say this with the understanding that I am not a quantum physicist, and therefore do not know the fullness of what's been discovered versus what's been theorized. I merely know that there are things unknown about it and posit the theory.

That's all I got. Go nuts.

 

[Satinavian]

The problem is that quantum thermodynamics and quantum field theory don't really change anything regarding this particular topic. They are only slightly more difficult to discuss (needing understanding of quantum interchangability, counting of states, uncertainty, entropy as information, entanglement and of course quantum decoherence).

Adding cosmology doesn't help too much either. Yes, inflation and so on makes counting of states difficult and we still don't really know what happened in the beginning, but thermodynamics is used in pretty much all cosmological models and yields the well known results.

CERN can make unique experiments, but those can be understood elsewhere. It is not as if they sit on secret unique knowledge - just the opposite. Experimental results get published as widely as possible.


Dark matter is irrelevant in this question. It behaves like matter. Dark energy is relevant as it is linked to cosmological properties of the empty space. But it is basically only a placeholder term for a mechanism we still don't know but of which we can describe the resulting properties - which are already used in our cosmological models.

 

[Laughing Man]

Now, we don't KNOW if the universe is a true infinity or not, because we just can't see that far, but... Given that the universe may be infinite, which is it that is true: That energy can be neither created nor destroyed, or that entropy will bring the total end of all that exists?

Uh no, the Universe isn't infinite and really it is that assumption that renders the rest of your thought process incorrect. The Universe is a measurable size and as far as we know may have the possibility to expand indefinitely. Since energy can neither be created nor destroyed it means that the amount of energy within the Universe a split second after the Big Bang is the amount that will be there throughout the Universe's life. If the Universe is constantly expanding then the amount of energy in it is being slowly spread out, thinned, entropy. At some point or another the Universe will be so large that the energy within it will be so thinly spread that it can no longer be reworked or changed in to making anything useful.

 

[Addendum_Forthcoming]

Now, we don't KNOW if the universe is a true infinity or not, because we just can't see that far, but... Given that the universe may be infinite, which is it that is true: That energy can be neither created nor destroyed, or that entropy will bring the total end of all that exists?

Uh no, the Universe isn't infinite and really it is that assumption that renders the rest of your thought process incorrect. The Universe is a measurable size and as far as we know may have the possibility to expand indefinitely. Since energy can neither be created nor destroyed it means that the amount of energy within the Universe a split second after the Big Bang is the amount that will be there throughout the Universe's life. If the Universe is constantly expanding then the amount of energy in it is being slowly spread out, thinned, entropy. At some point or another the Universe will be so large that the energy within it will be so thinly spread that it can no longer be reworked or changed in to making anything useful.

Yeah, but daven't they proven at this point that the universe is still accelerating? What scientists call the 'lambda' or dark energy still acting on a universe where gravity is a thing? I mean heat death with the premise of dark energy suggest a decay of the universe to the point of a purely photonic state which is like ... an ungodly number of years away.

Hence why scientists are contemplating the idea of the 'big rip' if things just keep on accelerating at the rate that they are? Basically spacetime tears itself apart due to the impossibility of a closed universe, and the fact that dark energy makes it far more plausible?

Also, doesn't GN-z11 basically put heat death at odds with current theoretical physics? I mean, oldest galaxy in the universe. Less than a 20th of the size of the Milky Way, with about <1% of our galaxy's mass ... forms new stars 20 times faster than the Milky Way...

(I am not an astrophysicist, please don't hurt me)

 

[Major_Tom]

Also, doesn't GN-z11 basically put heat death at odds with current theoretical physics? I mean, oldest galaxy in the universe. Less than a 20th of the size of the Milky Way, with about <1% of our galaxy's mass ... forms new stars 20 times faster than the Milky Way...

It WAS doing that 13.4 billion years ago. It might not even exist now.

 

[FalloutJack]

Big, Big Universe

Sorry to put you on the spot, but I needed to say that I stated so because we do not have a measurement of the universe, so we do not know where or if there are boundaries by any conceivable notion understandable to us. Our little planet and its technology just can't see it all, and with the possibility that it's all accelerating still, I can't conceivably say that a calculable size can be accurately modeled. I invoked infinity specifically for discussion purposes, to make things more streamlined. Please, continue.

OT: Discussion replies from me on subject will come later. Brain is tired.